Error was occurred while I was trying to open the Debug JS Remotely option in my iOS emulator.
The follow information was shown in react-native debug app:

I found these error information in my terminal running React packager：

But if i stop Remote JS Debugging, React Native App can run successfully.

I changed "localhost" in RCTWebSocketExecutor.m to the IP address of my computer (and restarting everything),but none of the solutions seem to work: